Electrical-apparatus core



Nov. 8, 1927. 1,648,705

E. A. WAGNER ELECTRICAL APPARATUS CORE Filed April 2. 1927 Inventor:

Edward A .wa gn GT,

His Attorney.

Patented Nov. 8 1927 UNITED s A Es PATENT OFFICE.

EDWARD A. WAGNER, OI PITTSEIEIYID, MASSACHUSETTS, ASSIGNOR '10 GENERAL ELEG- TRIG OOMPANY, A CORPORATION 01 NEW YORK.

ELECTRICAL-APPARATUS conn.

Application med April "2, 927; Serial 110. 180,586.

My invention relates to magnetic cores of electrical apparatus. To be eflicient, the magnetic 'core of a piece of electrical apparatus such as a transformer must be" of laminated construction and the laminations more or less well insulated from each other. This construction prevents excessive eddy currents with high losses in the core. The laminations are commonly secured together in a compact stack by means of belts or rivets extending through suitable openings in the laminations, these bolts or rivets being also insulated to prevent short circuiting the laminations. The usual bolt or rivet is circular in cross section and, with its insulation, obviously occupies an appreciable part of the cross section of the part of the core in which it is located. This increases the magnetic reluctance of the core and makes 0 necessary a larger core than would otherwise be required. Predetermination of the mag- .netic characteristics of .the core is also diflicult if a considerable portion of the cross section of the parts of the core is taken up by bolts or rivets. This proportion is greater in small than in large cores, so that the objection to the presence of the bolts or rivets is greatest in the small cores. The general object of the invention 80 is to rovide a core construction in which the dlsadvantag'es inherent in the round bolts and rivets heretofore used for securing the l'aminations together are reduced but without any sacrifice of strength.

The invention will be 'better understood from the following description taken in connection with the accompanying drawmg in which Fig. 1 is a perspective viewof a transformer with its core laminations secured together in accordancewith the invention and Fig. 2 is a view of the same transformer looking toward one face of the core,

a small part of one of the core yokes being broken away on the line 2 of Fig. 1.

Like reference characters indicate similar parts in both figures of the drawing.

The invention-will be described in connec tion' with the transformer shown in the drawin This transformer comprises a magnetlc core 10 having 'a winding leg 11,

yokes 12 two outer legs 13 joining the outer ends of the ,yokes, and windings 14 surrounding the winding leg 11; The core 10 is formed of a stack of magnetic laminations of suitable material such as silicon steel, these laminations being secured to-f gether in a tightly compressed unit by a pluralitv of rivets 15 distributed at suitable intervals" along the parts of the core,- The round rivets and bolts heretofore used for this purpose have been selected in as small sizes as was consistent with the necessary strength in order to take up as little as'pos- 'sible of the cross section of the core parts. In accordance with the present invention, the dimension of each rivet and bolt is still further reduced in the direction across the part of the core in which it is located or across theadjacent path of the magnetic flux and, in order that it maystill have the necessary strength, the dimension along this part of the core or'parallel with thepath of the flux is increased. This increase in the dimension of the rivet or bolt in the direction of the path of the magnetic flux has littleor no efl'ect on the reluctance of the magnetic circuit of the core and may be as great as necessary to provide a rivet or bolt with proper cross section and stren b. Each rivet or bolt is surrounded by a t in layer of insulation to avoid short circuiting the core laminations as 5 shown in Fig. 2 where a small section of the upper lammations is broken away and the cross sectional view of a rivet is shown with its layer of insulation indicated by. a heavy line. f While a particular form of electrical ap-' paratus has been described and illustrated with its core laminations secured together in accordance with the invention, it will .be apparent that various changes may be made within the scope of the invention as defined in the appended claims. -What 1 claim as new and desire to secure by Letters Patent of the United States, is 1. An electrical ap aratus core comprising a stack of magnetic aminations, and means extending through '0 enings in said lamina- 'tions for securing t em to ther, the cross 'g I I 1,648,705

across the ,core parts through which the sectional dimension of each of said securing extend being less thantheir cross sectional means across the adjacent ath of the magdimensions along said core parts. netic flux being less than its cross sectional 10 2. An electrical ap aratus core comprising dimension along said flux path. 5 a stack of magnetic aminations, and means In witness whereof, I have hereunto set extending through openings in said laminamy hand this 31st da of March, 1927. tions for securing them together, the cross EDW- D A. WAGNER. 

